Data generation apparatus, printing apparatus and data generation method

ABSTRACT

When a feeding amount for multi-pass printing is changed, the purpose related to an image quality using a binary data generation pattern can still be attained by, for example, a density pattern method. Specifically, a multi-pass printing mode is identified, and a density pattern selection matrix associated with a cycle of binary data generation is selected in accordance with the selected printing mode. That is, a density pattern selection matrix employed for binary data generation using a density pattern is changed to a size corresponding to the feeding amount designated by the selected printing mode. Thereby, a phenomenon that a unit used for image processing to gain a predetermined purpose related to an image quality does not match a unit area used for a printing operation is avoided, and an image printing purpose using a binary data generation pattern can be appropriately attained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data generation apparatus, a printingapparatus and a data generation method. Particularly, the presentinvention relates to processing for generating print data which is usedfor completing printing of a unit area of a printing medium byperforming a plurality of times of scans (movements) of a print head andby performing conveying of the printing medium between respective thescans (movements).

2. Description of the Related Arts

With the spread of information processing apparatuses such as personalcomputers, printing apparatuses that serve as image forming terminalshave also spread. Inkjet printing apparatuses especially, for performingprinting on a print medium such as paper, by ejecting ink onto themedium, through ejection ports, have the included advantages of beingnon-impact, reduced noise printing types, for which fast printing athigh densities are enabled, and of being easily compatible with colorprinting. Because of these advantages, inkjet printing apparatuses arerapidly becoming the favored, personal use printing apparatuses.

A so-called serial type inkjet printing apparatus frequently employs amulti-pass printing method. It should be noted that “pass” and “scan”used below have the same definition. According to the multi-passprinting method, image data for a predetermined area (unit area) isdivided into data for each color and each pass, and a mask is generallyemployed for this data division.

FIG. 1 is a diagram for explaining a multi-pass printing that employs amask, and illustrates a print head and printed dot patternsschematically for a case four scans are performed to complete printingof an image in a unit area. In FIG. 1, a reference sign P0001 denotes aprint head. To simplify the drawing and the explanation, the print headP0001 is shown to include a nozzle array of 16 ejection ports(hereinafter also referred to as nozzles). The nozzle array is dividedinto the first to the fourth nozzle groups, each of which includes fournozzles. A reference sign P0002 denotes a mask pattern. In the maskpatterns P0002, mask pixels (print permitting pixels) that permitprinting correspondingly to the individual nozzles are indicated bysolid black. The mask patterns corresponding to the four nozzle groupsare complementary to one another, and by superposing the four patterns,all of the 4×4 pixels become print permitting pixels. That is, the fourpatterns are employed to complete printing of the 4×4 area.

Reference signs P0003 to P0006 denote arrangement patterns of formeddots, which illustrate how an image is completed by repeating printingscans. As shown in these patterns, multi-pass printing forms dots basedon binary print data (dot data), which are generated by mask patternscorrespondingly to the nozzle groups, in each of printing scans. Theneach time a printing scan is completed, the printing medium is conveyeda distance, equivalent to the width of a nozzle group, in the directionindicated by an arrow in FIG. 1. By scanning four times in this manner,an image is formed in the area of the printing medium corresponding tothe width of each nozzle group.

According to the above described multi-pass printing method, unevenprint densities, which results from a variation in the ink ejectiondirections and ink ejection amount among multiple nozzles which are dueto manufacturing processes of the print head and from an error in paperconveying operation performed between the printing scans, can be madeless noticeable.

The example in FIG. 1 is for four-pass printing. The same process isperformed for two-pass printing, in which two scans are employed tocomplete the printing of an image, three-pass printing, in which threescans are employed to complete the printing of an image, or multi-passprinting, in which five or more passes are provided for five or morescans employed to complete the printing of an image. That is, thenumbers of ejection port groups provided by dividing ejection ports on aprint head and the amount a printing medium is conveyed, which arebasically explained while referring to FIG. 1, are determined inaccordance with the number of passes for completing printing.

Binary data (dot data) used for multi-pass printing is generated byemploying a pseudo gradation method, such as a density pattern method ora dither method. When the density pattern method is employed, severaltypes of density patterns having fixed dot arrangements are providedcorrespondingly to respective density levels. Then, a density patterncorresponding to an input density level is selected in accordance with adensity pattern selection matrix and thereby binary data is generated.When the dither method is employed, binary data is generated using adither pattern wherein threshold values are arranged in a predeterminedpattern.

The density pattern selection matrix and the dither pattern are notprepared as a pattern or matrix of the same size to that of binary datathat are expanded, but the density pattern selection matrix and thedither pattern having a predetermined size are repetitively used inaccordance with the overall size of the binary data to be expanded.

Conventionally, each of the repetitively used density pattern selectionmatrix and dither patterns is a single pattern size of which is fixed.According to Japanese Patent Laid-Open No. 2001-54956, a single patternhaving a fixed size is employed as a density pattern selection matrix(an index pattern) to perform multi-pass printing. As described in thisconventional example, when, for example, the number of passes formulti-pass printing is to be changed according to switching printingmodes, the conventional system that performs the multi-pass printingemploys a binarization pattern having a fixed size.

However, when a conventional binarization pattern (the density patternselection matrix, the dither pattern) having a fixed size is universallyemployed for a multi-pass printing system in which the number of passesis variable, following problems have arisen. More specifically, since apattern of fixed size may not be appropriate relative to the amount ofdistance which a printing medium is conveyed between respective scans(hereinafter this amount is also called a feeding amount), an imageprinting objective designed by the pattern, such as the printingquality, may not be achieved.

This problem is described below specifically. Binary data that isgenerated based on the density pattern selection matrix or the ditherpattern is generated in the cycle of repetition according to the size ofa density pattern selection matrix or a dither pattern.

In this case, when the feeding amount is integer multiple of the cycleof repetition of binary data generation (the binarization pattern), thesame repetition cycle for binary data is applied for all unit areas.Therefore, the deterioration of image quality does not occur due to adifference in the dot arrangements applied for the unit areas and adifference in the order of dot formation applied for the unit areas.However, when the feeding amount is not an integer multiple of therepetition cycle for binary data (the binarization pattern), therepetition cycle for the binary data appears in a different way amongthe unit areas. Further, the same repetition cycle for the binary datageneration corresponds to two adjacent unit areas, and therefore thebinarization pattern that is determined by taking into consideration theimage quality objective, especially the size of the binarizationpattern, operates over different unit areas. As a result, the dotarrangement and the dot forming order in a unit area may be madedifferent among the unit areas, and deterioration of the image qualitymay occur that is due to differences in the dot arrangements and in thedot forming order.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a data generationapparatus, a printing apparatus and a data generation method wherein,when a feeding amount for multi-pass printing is changed, the repetitivecycle for binary data generation (the binarization pattern) can appearin the same way for respective unit areas.

In a first aspect of the present invention, there is provided a datagenerating apparatus for generating binary data used for performingprinting on a printing medium by using a printing head in which aplurality of nozzles are arranged, the apparatus comprising: a settingpart for setting a printing mode, in which a plurality of movements ofthe printing head are performed and the printing medium is conveyed by aconveying amount smaller than an arranging width of the plurality ofnozzles of the printing head between each of the plurality of movements,to perform printing on an area corresponding to the conveying amount; aselection part for selecting a binarization pattern having a number ofpixels corresponding to a divisor of a number of pixels that correspondsto the conveying amount in the printing mode set by the setting part,from a plurality of binarization patterns that differ in a number ofpixels in a conveying direction of the printing medium from each other;and a generation part for generating binary data corresponding to thearea by using a binarization pattern selected by the selection part.

In a second aspect of the present invention, there is provided a datagenerating apparatus for generating binary data used for performingprinting on a printing medium by using a printing head in which aplurality of nozzles are arranged, the apparatus comprising: a settingpart for setting one printing mode in a plurality of printing modesincluding a first printing mode, in which M (M is an integer 2 orgreater) times of movements of the printing head are performed and theprinting medium is conveyed by a first conveying amount smaller than anarranging width of the plurality of nozzles of the printing head betweeneach of the M times of movements, to perform printing on an area havinga width corresponding to the first conveying amount and a secondprinting mode, in which N (N is an integer greater than M) times ofmovements of the printing head is performed and the printing medium isconveyed by a second conveying amount, which is smaller than the firstconveying amount, between each of the N times of movements, to performprinting on an area having a width corresponding to the second conveyingamount; and a generation part for, when the first printing mode is set,generating binary data corresponding to the area having the widthcorresponding to the first conveying amount by using a firstbinarization pattern having a number of pixels in a conveying directionof the printing medium, the number of pixels corresponding to a divisorof a number of pixels that corresponds to the first conveying amount,and when the second printing mode is set, generating binary datacorresponding to the area having the width corresponding to the secondconveying amount by using a second binarization pattern that differsfrom the first binarization pattern and has a number of pixels in theconveying direction, the number of pixels corresponding to a divisor ofa number of pixels that corresponds to the second conveying amount.

In a third aspect of the present invention, there is provided a printingapparatus for performing printing on a printing medium by using a printhead in which a plurality of nozzles are arranged, the apparatuscomprising: a setting part for setting one printing mode in a pluralityof printing modes including a first printing mode, in which M (M is aninteger 2 or greater) times of movements of the printing head areperformed and the printing medium is conveyed by a first conveyingamount smaller than an arranging width of the plurality of nozzles ofthe printing head between each of the M times of movements, to performprinting on an area having a width corresponding to the first conveyingamount and a second printing mode, in which N (N is an integer greaterthan M) times of movements of the printing head are performed and theprinting medium is conveyed by a second conveying amount, which issmaller than the first conveying amount, between each of the N times ofmovements, to perform printing on an area having a width correspondingto the second conveying amount; and a generation part for, when thefirst printing mode is set, generating binary data corresponding to thearea having the width corresponding to the first conveying amount byusing a first binarization pattern having a number of pixels in aconveying direction of the printing medium, the number of pixelscorresponding to a divisor of a number of pixels that corresponds to thefirst conveying amount, and when the second printing mode is set,generating binary data corresponding to the area having the widthcorresponding to the second conveying amount by using a secondbinarization pattern that differs from the first binarization patternand has a number of pixels in the conveying direction, the number ofpixels corresponding to a divisor of a number of pixels that correspondsto the second conveying amount.

In a fourth aspect of the present invention, there is provided a datagenerating method of generating binary data used for performing printingon a printing medium by using a print head in which a plurality ofnozzles are arranged, the method comprising: a setting step of setting aprinting mode, in which a plurality of movements of the printing headare performed and the printing medium is conveyed by a conveying amountsmaller than an arranging width of the plurality of nozzles of theprinting head between each of the plurality of movements, to performprinting on an area corresponding to the conveying amount; a selectionstep of selecting a binarization pattern having a number of pixelscorresponding to a divisor of a number of pixels that corresponds to theconveying amount in the printing mode set by the setting step, from aplurality of binarization patterns that differ in a number of pixels ina conveying direction of the printing medium from each other; and ageneration step of generating binary data corresponding to the area byusing a binarization pattern selected by the selection part.

According to the above configuration, even if a feeding amount formulti-pass printing is changed, the repetition cycle for binary datageneration (the binarization pattern) can be applied in the same way foreach unit area. Thereby, a dot arrangement and dot forming order for aunit area can be identically applied for respective unit areas, anddeterioration of the image quality will not occur due to differences inthe dot arrangements and in the dot forming orders.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a multi-pass printing methodthat employs a print head and printed dot patterns;

FIG. 2 is a diagram showing a relationship between a print head and aprinting medium when two-pass printing is to be performed;

FIGS. 3A and 3B are diagrams for explaining a case, according to a firstembodiment of the present invention, wherein two-pass printing is to beperformed using C, M and Y ink;

FIG. 4 is a block diagram that mainly illustrates the hardware andsoftware configurations of a personal computer that serves as an imageprocessing apparatus according to the first embodiment;

FIG. 5 is a flowchart showing the image processing performed for thefirst embodiment;

FIG. 6 is a diagram showing a density pattern employed for the firstembodiment;

FIG. 7 is a diagram for explaining a relationship, for the firstembodiment, between a repetitive generation cycle for binary data and afeeding amount;

FIG. 8 is a schematic diagram showing a relationship between a printhead and a printing medium for three-pass printing;

FIG. 9 is a diagram for explaining a relationship between a feedingamount and a repetitive generation cycle for a case wherein a repetitivegeneration cycle for binary data is not a divisor of the feeding amount;

FIG. 10 is a diagram showing a relationship between a feeding amount anda repetition cycle for three-pass printing according to the firstembodiment;

FIG. 11 is a flowchart showing the processing, for the first embodiment,performed to change a repetitive generation cycle for binary data inassociation with a change in the number of passes employed formulti-pass printing;

FIGS. 12A to 12D are diagrams for explaining the interference producedby a mask pattern employed for the quantization of print data;

FIGS. 13A to 13D are schematic diagrams illustrating the processing forthe calculation of a repulsive force potential and the attenuation ofthe total, available energy;

FIG. 14 is a schematic diagram showing a function of a basic repulsivepotential E(r), according to a second embodiment of the presentinvention;

FIG. 15 is a flowchart showing the processing, according to the secondembodiment, performed to arrange print permitting pixels using asequential arrangement method;

FIG. 16 is a conceptual diagram, for the second embodiment, for thecalculations performed for a mask C;

FIG. 17 is a diagram showing dot arrangement patterns based on indexdata;

FIG. 18 is a diagram showing patterns, based on the dot arrangementpatterns shown in FIG. 17, that should be taken into account for thefabrication of a mask;

FIG. 19 is a diagram showing other dot arrangement patterns, accordingto the second embodiment, that are based on index data;

FIG. 20 is a diagram showing patterns, based on the dot arrangementpatterns shown in FIG. 19, that should be taken into account forfabrication of a mask; and

FIG. 21 is a diagram showing an example density selection matrix.

DESCRIPTION OF THE EMBODIMENTS

The preferred embodiments of the present invention will now be describedin detail while referring to the accompanying drawings.

A printer used as an inkjet printing apparatus according to a firstembodiment of the present invention selectively perform a plurality ofprinting modes, for which a different number of passes and differentconveying amounts are used in multi-pass printing. As will be describedlater while referring to FIG. 11, the repetition cycle for generation ofbinary data (repetition cycle of binarization pattern) is changed inaccordance with the feeding amount of a printing medium that correspondsto a selected printing mode.

FIG. 2 is a schematic diagram showing a relationship between a printhead and a printing medium in a two-pass printing mode of printing modesto be performed by a printer according to this embodiment. In thetwo-pass printing mode, a print head scans a printing medium twice tocomplete printing of an image in the unit area on the printing medium.

Respective color nozzle arrays for cyan, magenta and yellow are dividedinto a first group and a second group that include 256 nozzles each.Therefore, the number of nozzles for one color is 512. When the printhead scans the printing medium in directions (“head scanning directions”indicated by a double-headed arrow in FIG. 2) substantiallyperpendicular to the nozzle array direction, ink is ejected from thecolor nozzle arrays to the individual unit areas of the printing mediumeach of which corresponds to the array widths of each nozzle group. Inthis example, based on C, M and Y binary image data, C, M and Y ink isejected to the individual unit areas. Further, when scanning is ended,the printing medium is conveyed by an amount equivalent to the width ofone group (in this case, the length of 256 pixels equivalent to thewidth of the unit area) in a direction (here, a “printing mediumconveying direction” indicated by an arrow in FIG. 2) perpendicular to(across) the head scanning direction. Thus, an image has been printed ineach unit area by two scans. Hereinafter, the conveying amount which theprinting medium is conveyed between a plurality of scans to completeprinting of an image is also called a feeding amount. As shown in FIG.2, the feeding amount (conveying amount) is represented as an amountequivalent to a length of Nf (=256) pixels.

The two-pass printing mode will now be more specifically described. Atthe first scan, an area A of the printing medium is printed by employingthe respective first groups of the C nozzle array, the M nozzle arrayand the Y nozzle array in the named order. Then, at the second scan, theremaining data is printed on the area A that has been printed by thefirst scan, by using the respective second groups of the Y, M and Cnozzle arrays in the named order. Further, a nonprinted area B isprinted by employing the respective first groups of the Y, M and Cnozzle arrays in this order.

This processing is repeated to perform printing to the respective unitareas (the area A and the area B) in the order of C1, M1, Y1, Y2, M2 andC2, or the order of Y1, M1, C1, C2, M2 and Y2.

FIGS. 3A and 3B are diagrams for explaining the order of printing a unitarea for a case wherein, as shown in FIG. 2, two-pass printing is to beperformed using C, M and Y ink.

In FIG. 3A is shown the process for printing an image in an area (thearea A in FIG. 2) in the order of forward scanning and backwardscanning. At the forward scanning (first pass) that is the firstscanning, first of all, a cyan image is printed based on cyan dot datathat is generated for each pass using a mask, as will be described laterwhile referring to FIG. 5. Sequentially, magenta and yellow images areprinted by the same scan, based on dot data that is also generated usingthe mask in the same manner. That is, the magenta image is superposedwith the previously printed cyan image, and the yellow image is printedby being superposed with the cyan and magenta images. The printingmedium is conveyed a predetermined amount, and then, the same processingis performed at the backward scanning (second pass) that is the secondscan. That is, based on yellow, magenta and cyan dot data generated foreach pass using a mask, images are printed by being superimposed withthe images that were previously printed.

In FIG. 3B is shown the process until completion of printing of an imagein an area (the area B in FIG. 2) for which printing is performed in theorder of backward scan and forward scan. At the backward scan (firstpass) that is the first scanning, a yellow image is printed based onyellow dot data that is generated based on a mask for each pass.Following this, at the same scanning, magenta and cyan images areprinted based on dot data that is generated using the mask for the passin the same manner. That is, the magenta image is printed by beingsuperposed with the yellow image that was previously printed, and thecyan image is printed on the yellow and magenta images that werepreviously printed. Then, in the forward scan (second pass) that is thesecond scanning after the printing medium is conveyed a predeterminedamount, similarly, cyan, magenta and yellow dot data generated in theabove described manner are employed, and images are sequentially printedon the images that were previously printed.

FIG. 4 is a block diagram mainly illustrating the hardware and softwareconfiguration of a personal computer (hereinafter simply referred toalso as a PC) that is an image processing apparatus (data generationapparatus) according to this embodiment. In this embodiment, a computer100, to which a printer driver 103 is installed to perform the binarydata generation processing shown in FIG. 11 that will be describedlater, is defined as an image processing apparatus (data generationapparatus). However, the image processing apparatus (data generationapparatus) of this invention is not limited to this configuration. Forexample, when a printer 104 performs the binary data generationprocessing that is the feature of the invention, the printer 104 servesas an image processing apparatus (data generation apparatus).

In FIG. 4, the PC 100 that is a host computer employs an operatingsystem (OS) 102 to operate individual software products, such asapplication software 101, the printer driver 103 and a monitor driver105. The application software 101 performs processes related to wordprocessing, a spreadsheet program and an Internet browser. The monitordriver 104 performs a process, such as creation of image data to bedisplayed on a monitor 106.

The printer driver 103 processes image data and the like that are issuedfrom the application software 101 to the OS 102, and generates binaryejection (dot) data that is finally employed by the printer 104.Specifically, the printer driver 103 performs the processing that willbe described later while referring to FIG. 5 and FIG. 11, so as to basedon C, M and Y multi-level image data, generate C, M and Y binary imagedata used by the printer 104. The thus obtained binary image data aretransferred (supplied) to the printer 104.

The host computer 100 includes a CPU 108, a hard disk drive (HD) 107, aRAM 109 and a ROM 110, which are hardware components to operate theabove described software products. That is, the CPU 108 performs theprocessing in accordance with the software program stored on the harddisk 107 or in the ROM 110, and employs the RAM 109 as a work area whenperforming the processing.

As described while referring to FIG. 2, the printer 104 in thisembodiment is a so-called serial printer that moves a print headrelative to a printing medium for scanning, and ejects ink from theprint head during scanning to perform printing. A print head thatincludes ejection port groups for C, M and Y ink colors is mounted to acarriage, and scans a printing medium, such as a sheet of paper.Printing elements, such as electrothermal converting elements orpiezoelectric elements, are provided in ink flow paths that communicatewith the individual ejection ports respectively in the print head, andby driving these printing elements, ink is ejected from the ejectionports. The arrangement density of the ejection ports is 1200 dpi, andink of 3.0 picoliter is ejected from each ejection port. Further, 512ejection ports are provided for each color nozzle array.

The printer 104 includes a CPU and a memory (neither of then shown), andbinary image data received from the host computer 100 is received in thememory of the printer 104. The CPU reads binary image data from thememory and transfers the drive circuit of the print head, and based onthe binary image data, the drive circuit drives the print elements ofthe print head to eject ink from the ejection ports.

In the embodiment of the present invention, the density pattern methodis employed to generate binary data for six planes that aredistinguished by forward and backward scans and C, M and Y ink colors inthe multi-pass printing mode. FIG. 5 is a flowchart showing the binarydata generation processing.

In FIG. 5, first, a color adjustment process is performed for RGB 8 bitdata (S401), and CMY image data of 8 bit are obtained by performing acolor conversion process (S402). Then, a gamma correction process (S403)is performed for the image data.

Following this, the CMY 8 bit image data of 256 levels obtained throughthe above processes, are quantized by error diffusion, and 5-valued(levels) data of 3-bit is obtained (S404). Then, based on 5-level data,binary data expansion is performed using a density pattern (dotarrangement pattern) shown in FIG. 6 (S405). It should be noted that the5-level data obtained at step S404 has a resolution of 600 dpi for onepixel, while the density pattern (dot arrangement pattern) employs 2×2pixels as one unit. Therefore, the resolution of the generated binarydata is 1200 dpi×1200 dpi.

FIG. 6 is a diagram showing density patterns according to thisembodiment. As shown in FIG. 6, four density pattern types are providedfor each density level of 5-level data. In the binary data expansionprocess, depending on the density level indicated by the 5-level data, adensity pattern is selected in accordance with the pattern typeindicated by a density pattern selection matrix, and is employed as a2×2 pixel unit of binary data. For example, when the density levelindicated by 5-level data is “1” and the value of a density patternselection matrix is “0”, a 0-th density pattern is selected from amongfour types of density pattern level 1 (in 2×2 pixels, one dot is ON). Byrepeating this process, a binary image is generated at the resolution of1200 dpi x1200 dpi.

In this embodiment, the density pattern selection matrix pattern shownin FIG. 21 is employed as a binarization pattern. The density patternselection matrix of this embodiment has a size of 32×32 pixels, and fourvalues from 0 to 3 are irregularly entered in the individual pixels.Based on the pixel values of “0” to “3”, the density pattern of 2×2pixels is expanded, for the individual pixels of the density patternselection matrix. That is, in accordance with the 32×32 pixel size ofthe density pattern selection matrix, the binary data (dot) pattern of1200×1200 dpi is changed to a pattern of 64 pixels (main scanningdirection)×64 (feeding direction) pixels cycles. Assuming that the sizeof a density pattern selection matrix is 100×100 pixels, binary datapattern is expanded into a pattern of 200×200 pixels cycles. In the sizeor cycle changing process for embodiments of the invention that will bedescribed later, the size of a pattern that has been expanded using thedensity pattern selection matrix is focused on. However, the sameprocess can also be applied for the size or the cycle for the densitypattern selection matrix per se.

Referring again to FIG. 5, finally, based on binary data obtainedthrough the binary data expansion, binary data respectively for the sixplanes are obtained using masks (S406).

Furthermore, it is apparent from the description below that the presentinvention can also be applied for a case wherein ink of four colorsincluding black (Bk) is employed in addition to C, M and Y, or whereinink including light ink having a low concentration or ink of specialcolors, such as red, blue and green, are employed.

First Embodiment

According to a first embodiment of the present invention, one printingmode that is selected from a plurality of printing modes between whichthe number of passes for multi-pass printing is different is set, and afeeding amount corresponding to the selected printing mode isdetermined. Then, to use a density pattern selection matrix of a sizecorresponding to the determined feeding amount, one matrix having theabove size is selected from a plurality of density pattern selectionmatrixes.

As described while referring to FIG. 2, in the two-pass printing mode inthis embodiment, the feeding amount Nf is equivalent to the length of256 pixels because of the number of nozzles (512) provided for the printhead. According to this feeding amount, in the two-pass printing mode,the size of the density pattern selection matrix in the feedingdirection is defined as the length of 32 pixels, and a repetition cycleNg of binary data in the feeding direction to be expanded using adensity pattern matrix is defined as the length of 64 pixels. That is,the feeding amount Nf is the integer multiple of the repetition cycleNg, i.e., the repetition cycle Ng (=64 pixels) is defined as a divisorof the feeding amount Nf (=256 pixels).

FIG. 7 is a diagram for explaining a relationship between the repetitioncycle and the feeding amount. As shown in FIG. 7, the upper ends ofareas A, B, - - -, each of which is a unit area for which printing iscompleted by a plurality of scans, always match the same position(pixel) in the repetition cycle.

Next, a description will now be given for a case where the number ofpasses for multi-pass printing is changed to three passes by changing ofthe printing mode or the like.

FIG. 8 is a diagram for explaining three-pass printing, andschematically showing a relationship between a print head and a printingmedium. As will be described below, in the three-pass printing mode, aprinting head scans a printing medium three times to complete printingof an image in a predetermined unit area of the printing medium.

Cyan, magenta and yellow nozzle arrays are respectively divided intofirst, second and third groups, each of which includes 168 nozzles. Inthis embodiment, a value of 168 is selected because this is close to170, which is obtained by dividing 512 nozzles (corresponding to pixelsin this case) by three.

The print head scans the printing medium in a direction (“head scanningdirection” indicated by a double-headed arrow in FIG. 8) perpendicularto a nozzle arrangement direction, and ejects ink from the nozzle arraysto the unit areas each of which corresponds to the widths of the nozzlearrays of each of the nozzle groups. In this example, based on C, M andY binary image data, C, M and Y ink is ejected to the individual unitareas. Further, when scanning is ended, the printing medium is conveyedin a direction (“printing medium conveying direction” indicated by anarrow in FIG. 8) perpendicular to (across) the scanning direction of theprint head, an amount equivalent to the width of one nozzle group, i.e.,the feeding amount=the length of 168 pixels. Then, the same operation isrepeated once more, and printing for the individual unit areas iscompleted by three scans.

At this time, assume that the repetition cycle Ng (=64) of binary datageneration is not a divisor of the feeding amount Nf (=168 pixels),i.e., assume that the repetition cycle is not to be changed. FIG. 9 is adiagram for explaining a relationship between a feeding amount Nf and arepetition cycle Ng in this case.

Assume that a beginning position of the area A is defined as 0, andmatches the beginning position of the repetition cycle. At this time,the beginning position of the area B represents coordinate 168 in thefeeding direction that is equivalent to the feeding amount (for 168pixels). When the repetition cycle Ng is equivalent to the length of 64pixels, the beginning coordinates 168 of the area B is not divisible by64, unlike in the two-pass printing case. That is, binary data atdifferent positions (pixels) in the repetition cycle are as a wholerelated to the area A and the area B respectively. Further, after theprinting medium is conveyed the length of 168 pixels, the beginningcoordinate 340 is obtained for the area C. This indicates that thebinary data generation cycle is shifted, and likewise, binary data atdifferent locations (pixels) in the repetition cycle are wholly relatedto two areas. When the feeding amount Nf is not the integer multiple ofthe repetition cycle Ng in this manner, the repetition cycle of binarydata generation (binarization pattern) appears in different way betweenthe unit areas. Then, the arrangement of dots and the order of formingdots for a unit area become different between the unit areas. As aresult, a deterioration of an image might occur due to the difference inthe arrangement of dots and the order of forming dots.

According to this embodiment, when the number of passes for multi-passprinting is changed, the feeding amount that is changed in response tothe change of the number of passes is employed to change the repetitioncycle Ng of binary data generation. In this embodiment, for three-passprinting, the repetition cycle Ng should be 84 that is a divisor of thefeeding amount Nf (=168 pixels). Specifically, for three-pass printingshown in this example, a matrix of 42 pixels (the main scanningdirection; the head scanning direction)×42 pixels (the feedingdirection; the printing medium conveying direction) for three-passprinting, which is different from a two-pass printing matrix, isemployed as a density pattern selection matrix. Further, the densitypattern is defined as the size of 2 pixels×2 pixels. Therefore, when thedensity pattern expanding process is performed, binary data of 84 pixelsis generated both in the scanning direction and in the feedingdirection.

It is preferable that, as will be described later, a value greater thanthe smallest value of 32 is selected as a divisor. That is, it iseffective that a density pattern method should be designed to prepare aplurality of density patterns in accordance with density levels, so thata cycle for selecting these density patterns will not become regular.With pattern irregularity, overlapping of dots when the dot printingposition is deviated can be prevented from being changed. In order toperform irregular selection of the density pattern, the cycle or thesize of the density pattern selection matrix should be increased to adegree. According to the study of the present inventors, at least adensity pattern selection matrix of 32 pixels is preferable. In thisembodiment, the density pattern selection matrixes corresponding to thefeeding amounts are prepared in advance. However, the present inventionis not limited to this aspect. For example, only one density patternselection matrix (e.g., 100 pixels×100 pixels) larger than a sizeemployed for each feeding amount may be prepared, and may be cut into apattern size corresponding to the feeding amount. As an advantage ofthis aspect, a plurality of density pattern selection matrixes ofdifferent sizes need not be prepared in advance.

FIG. 10 is a diagram showing a relationship between the feeding amountNf and the repetition cycle Ng for the three-pass printing of thisembodiment. As shown in FIG. 10, when the feeding amount is changed toan amount equivalent to a length of 168 pixels, the repetition cycle isalso changed to a repetition cycle equivalent to a length of 84 pixels.

According to the above configuration, an image printing purpose, such asthe improvement of an image quality, to be achieved using a densitypattern, can be appropriately attained. More specifically, the densitypattern selection matrix is prepared in which the dot arrangement andthe pattern size are determined by the matrix size, so that apredetermined purpose related to an image quality can be attained. Theunit area for which printing is completed by multi-pass printing is aunit for which various conditions of the printing operation, such as theorder of using the nozzles of the print head, are designated. A unitused for image processing to attain a predetermined purpose related tothe image quality is made match a unit used for the printing operation,and thereby an image printing purpose using a binary data generationpattern can be appropriately attained.

FIG. 11 is a flowchart showing the binary data generation processingaccording to this embodiment, especially, the processing for relating arepetition cycle of binary data generation to the number of passes formulti-pass printing and a conveying amount.

First, in a host apparatus, one printing mode is selected from aplurality of printing modes, for which different conveying amounts anddifferent numbers of passes are designated (S1201). The printing modemay be selected by a user, or may be automatically by a host based onimage data. Thus selected printing mode is set in the host as anoperating mode to be used for printing. Available printing modes may bethree or more, and for simplification of the description, it is assumedin the following description that two printing modes are available.

Sequentially, a check is performed to determine whether the printingmode set in the host is a first printing mode or a second printing mode(S1202). The first printing mode is a mode that performs two-passprinting as explained while referring to FIGS. 2 and 7. Specifically,the first printing mode is a mode in which printing for a unit areahaving a width corresponding to a first conveying amount in theconveying direction is completed by performing M scans (M is an integerof 2 or greater, and M=2 in this case) and by performing a conveying ofa printing medium by the first conveying amount (feeding amount; Nf=256pixels) between the M scans. On the other hand, the second printing modeis a mode that performs three-pass printing as explained while referringto FIGS. 8 and 10. Specifically, the second printing mode is a mode inwhich printing for a unit area having a width corresponding to a secondconveying amount in the conveying direction is completed by performing Nscans (N is a different integer from N and 2 or greater, and N=3 in thiscase) and by performing a conveying of a printing medium by the secondconveying amount (feeding amount; Nf=168 pixels) between the N scans.

When it is determined at step S1202 that the first printing mode is set,processing control advances to step S1203, and a first density patternselection matrix (first binarization pattern) is selected as a densitymatrix pattern for use. As described while referring to FIGS. 7 and 21,the size of the first density pattern selection matrix (firstbinarization pattern) is 32 pixels×32 pixels (64 pixels×64 pixels forbinary data), which is a divisor of the first conveying amount (Nf=256pixels). Therefore, the repetition cycle Ng of binary data generationand the size of binarization pattern can be made respective divisors ofthe first conveying amount (Nf=256 pixels). Then, a binarization processis performed using the first density pattern selection matrix togenerate binary data (S1204). The binary data generation process atS1204 corresponds to the binarization process at S405 in FIG. 5.Following this, using a mask for two-pass printing, the binary datagenerated at step S1204 is divided into two scans, so that binary datafor two-pass printing are obtained in accordance with two scans (S1205).The binary data division process at S1205 corresponds to the passdivision process at 5406 in FIG. 5.

When it is determined at step S1202 that the second printing mode isset, on the other hand, processing control is shifted to step S1206, anda second density pattern matrix (second binarization pattern) isselected as a density pattern matrix for use. As described whilereferring to FIG. 10, the size of the second density pattern selectionmatrix (second binarization pattern) is 42 pixels×42 pixels (84pixels×84 pixels for binary data), which is a divisor of the secondconveying amount (Nf=168 pixels). Therefore, the repetition cycle Ng ofbinary data generation and the size of the binarization pattern can bemade respective divisors of the second conveying amount (Nf=168 pixels).Then, the binarization process is performed using the second densitypattern selection matrix, and binary data is generated (S1207). Thebinary data generation process at S1207 corresponds to the binarizationprocess at S405 in FIG. 5. Sequentially, using a mask for three-passprinting, the binary data generated at step S1204 is divided for threescans, and binary data for three-pass printing are obtained inaccordance with three scans (S1208). The binary data division process atS1208 corresponds to the pass division process at S406 in FIG. 5.

As described for this embodiment while referring to FIGS. 7 to 10, therepetition cycle of binary data generation or the size of thebinarization pattern is changed when the feeding amount is changed inassociation with the change of the number of passes. At this time, therepetition cycle of binary data generation or the size of thebinarization pattern is changed to be a divisor of a feeding amount.Thereby, the repetition cycle of binary data generation (binarizationpattern) can appear in all the unit areas in the same way. Therefore,non-matching is avoided between a unit (repetition cycle) for imageprocessing, to attain a predetermined purpose related to an imagequality, and an area (a unit area) for a printing operation, and theimage printing purpose intended by a pattern for a binary datageneration can be appropriately attained.

In this embodiment, the two-pass printing mode has been employed as thefirst printing mode, and the three-pass printing mode has been employedas the second printing mode. However, the number of passes used in thisembodiment is not limited to these. For example, the first printing modemay be a four-pass mode and the second printing mode may be a three-passmode. Further, the third printing mode may also be prepared, and thefirst printing mode may be a two-pass mode, the second printing mode maybe a three-pass mode, and the third printing mode may be a four-passmode. So long as a repetition cycle of binary data generation is adivisor of a conveying amount, any form can be employed.

As described above, according to this embodiment, binary data isgenerated to be employed for multi-pass printing, in which a print headscans a printing medium by a plurality of times while a printing mediumis conveyed between respective scans, so that printing is completed in aunit area of the printing medium. For binary data generation, a densitypattern in a density pattern selection matrix, which is patterncontaining information for binary data generation is employed. Whenmulti-pass printing modes, for which different conveying amounts aredesignated, are to be performed, a density pattern selection matrixresponding to the conveying amount is selected, so that a repetitioncycle of binary data generation in the conveying direction, of thedensity pattern selection matrix can be a divisor of the conveyingamount. Asa result, regardless of whether the conveying amount ischanged, the repetition cycle of binary data generation is a divisor ofthe conveying amount. So long as this relationship is maintained, animage deterioration does not occur.

Second Embodiment

In a second embodiment of the present invention, as well as the firstembodiment, a repetition cycle of binary data generation is changed inaccordance with a change of a feeding amount. However, the contents ofmasks of individual colors are different in order to divide binary datafor a plurality of scans. These masks are disclosed in Japanese PatentLaid-Open No. 5-31922 and Japanese Patent Laid-Open No. 2007-306551 bythe applicant of the present application. These disclosed masks arecreated while taking into account the interference between a densitypattern selection matrix and masks.

For the configuration wherein print data is generated using a mask thatcorresponds to a unit area for which printing is completed by multi-passprinting, an interference between a mask pattern and print data mayoccur.

FIGS. 12A to 12D are diagrams for explaining this interference problem.In FIG. 12A, a pattern for cyan binary data is shown, and in FIG. 12B,of two-pass mask cyan patterns, a cyan mask pattern for the first pass(50% is print permitting pixels) is shown. The size of the binary datapattern in FIG. 12A is 4 pixels×4 pixels, while the mask pattern in FIG.12B has a size of 4 pixels×4 pixels in which print permitting pixels arearranged and has a pattern of pixels that are located in one to onecorrespondence to pixels in the binary data pattern.

In this case, at the first pass, AND data of the mask pattern and thebinary data pattern, i.e., a dot pattern shown in FIG. 12C, is printed.That is, according to binary data in FIG. 12A, there are four dots to beformed, but 0 dots are actually formed at the first pass. On the otherhand, at the second pass shown in FIG. 12D, the four remaining dots areformed. As described above, an interference occurs between the maskpattern and binary data (dot data), and thus, dots are unevenly formedin a specific scan. That is, dots are not evenly dispersed to aplurality of scans, and various adverse affects are provided, e.g., theoriginal effects of multi-pass printing are not sufficientlydemonstrated. For example, when ink is unevenly ejected in a specificscan due to this interference, ink dots are connected before beingabsorbed on a printing medium, and so-called beading occurs. Thus, theimage quality is deteriorated, e.g., a grainy image appears.

There is the opposite case to the example shown in FIG. 12. That is,four dots are formed at the first pass, and 0 dots are formed at thesecond pass. Further, the interference occurs not only due to the datasize, but also due to a combination of various binary data patterns andcorresponding pass mask patterns.

Methods for solving this interference are described in Japanese PatentLaid-Open No. 5-31922 and Japanese Patent Application No. 2007-104268.According to these methods, when determining a mask pattern, thearrangements of print permitting pixels are determined based on thearrangement characteristic of ON (“1”)/OFF (“0”) in binary data. Forexample, when the binarization process is performed using a densitypattern method, pixels for which binary data will be ON at theintermediate gradation can be roughly identified based on the dotarrangement characteristic in the density pattern. Therefore, thepositions of print permitting pixels can be determined in a mask patternby considering the interference of these positions and the positions ofdots in the density pattern. Thus, the interference between the maskpattern and the print data can be reduced.

However, when a feeding amount is changed, binary data generated by thedensity pattern method might not be appropriate even though the abovedescribed mask is employed. More specifically, the density patternselection matrixes are repetitively used and binary data is generated atthe repetition cycle according to the sizes of the matrixes. In thiscase, depending on a relationship between the repetition cycle of binarydata generation and the feeding amount that has been changed, decreasingof the interference between print data and the mask, which is disclosedin Japanese Patent Laid-Open 5-31922 and Japanese Patent Application No.2007-104268, may not be effectively performed. As a result, the binarydata thus generated is not appropriate to be used for reducing theinterference between the mask and the binary data.

Specifically, when the feeding amount is not the integer multiple of therepetition cycle of binary data generation, binary data present in onecycle might correspond to both a certain unit area and adjacent unitarea to the certain unit area, for which printing is completed in themulti-pass printing. As a result, binary data at different positions(pixels) in the repetition cycle wholly correspond to the same mask thatis used for printing the two areas. In this case, it is not effectivethat, as described in the patent publications, the positions of printpermitting pixels for a mask are determined by considering theinterference with binary data. Further, the interference between printdata and the mask can not be appropriately reduced.

Because of these viewpoints, in this embodiment, the same processing asin the first embodiment is performed in the configuration wherein a maskis prepared and employed by considering an interference between adensity pattern selection matrix and a mask. That is, when the feedingamount is changed in accordance with a unit area wherein printing imageis completed, the repetition cycle of binary data generation is alsochanged.

A mask used for this embodiment is the one prepared by a methoddescribed in Japanese Patent Application No. 2007-104268. The method formanufacturing the mask will now be described.

A method of creating a mask that is used or created in a printing systemaccording to this embodiment and several examples of the mask will bedescribed below. Before that, a basic method for mask creation and aconcept of calculation of repulsive force used in the method for maskcreation will be described.

(Method of Creating Mask)

In the basic method for creating a mask described below, both a mask inwhich print permitting pixels are arranged and a dot arrangement patternin which dots are arranged and which has the same size as that of themask are referred as “plane” in order to simplify the description. Bothprint permitting pixels and dots that are arranged in these patterns arereferred as simply “dot”.

In the method of creating the masks according to the embodiment of theinvention, for the planes of the masks and the dot arrangement pattern,first, the three planes of planes A1, A2 and A3 are set as shown inFIGS. 13A-13D. Then, repulsive forces are exerted between the dotswithin the identical plane and between the dots in the respectivedifferent planes. Also, the superposition of the dots of the differentplanes is permitted, and a repulsive force is exerted between suchsuperposed dots. Thus, the arrangements of the dots within therespective planes are determined.

A method of determining the arrangements of the dots in the planes isbroadly classified into two methods; a method which simultaneouslydetermines arrangements of a plurality of planes (simultaneousgeneration), and a method which sequentially determines the arrangementsof the respective planes (plane-by-plane generation). Moreover, for eachof the above two generation methods, a manner of determining thearrangement of dots includes a method of arranging all the dots in theplane in a predetermined way and moving the arrangement, while makingthe entire plane being generated more dispersive (this method ishereinafter be referred to as an “arrangement moving method”). As othermethod, a method can be executed in which each dot is placed whilemaking the entire plane being generated more dispersive (this method ishereinafter referred To as a “sequential arrangement method”).

Arrangement Moving Method

The outline of an arrangement determination process for dots that isbased on the arrangement moving method is as stated below.

For example, in case of determining the arrangements of the dots in theplane whose arrangement rate is 50%, an initial arrangement in which 1bit data each being “1” are allocated at 50% of allocable positions isobtained by a binarization process, such as an error diffusion method,as to each of planes A1, A2 and A3. It should be noted that the reasonswhy the initial arrangements of the dots are obtained by employing thebinarization technique are that the arrangements whose dispersiveness isfavorable in an initial state to some extent can be obtained incorrespondence with the binarization technique employed, and that acalculation time period or convergence time period till the finalarrangement determination can be shortened in this way. In other words,the method of obtaining the initial arrangements is not essential inapplying the present invention, but it is also allowed to adopt, forexample, an initial arrangement in which the 1 bit data being “1” areallocated at random in the plane.

Then, a repulsive potential is calculated for all the dots in each ofthe planes A1, A2, A3 obtained as described above. Specifically,

(i) Repulsive force is applied to the dots of the same plane dependingon the distance between these dots.

(ii) Also, repulsive force is applied to the dots of different planes.

(iii) Different repulsive force is applied for the same plane and thedifferent planes.

(iv) Dots of different planes are allowed to overlap one another, andrepulsive force is applied to overlapping dots (two, three, or moredots) according to combinations of the overlapping dots.

FIG. 14 is a diagram schematically showing a function for a basicrepulsive potential E(r) according to the present embodiment.

As shown in FIG. 14, for the repulsive force function that is defined inthe present embodiment, the coverage of the repulsive force is up tor=16 (16 positions on which dots are arranged). The potential thatattenuates depending on the distance basically brings a high energystate, that is, an unstable state when dots are arranged close to oneanother. Thus, the convergence calculation makes it possible to avoidselection of a dense arrangement as much as possible. The shape of therepulsive force is more desirably determined by the ratio of the dots toall the allocable positions.

Further, in the case of considering the arrangement of the dot in whichplural dots overlap one another, it may occur that the number ofpositions where dots are arranged exceed that of positions where dotscan be arranged (for a resolution of 1200 dpi (dot/inch), 1200×1200possible positions in a 1-inch square), and then the arranged dots aremade overlapped each other. Accordingly, in calculating the repulsivepotential of each dot, considerations need to be given for possibleoverlapping of dots each other. Thus, the function is defined so as tohave a finite repulsive potential at r 0. This enables dispersion withpossible overlapping of dots taken into account.

The present embodiment executes calculations such that a repulsivepotential αE(r) is applied to the dots on the same plane, a repulsivepotential βE(r) is applied to the dots on different planes, and arepulsive potential γs(n)E(r) is applied to overlapping dots. Morespecifically, a repulsive potential resulting from the presence of acertain dot is what is obtained by adding following potentials to theabove repulsive potential: the repulsive potentials of dots on the sameplane, dots on different planes, and an overlapping dots on differentplanes, respectively within the distance r from the certain dot.

For the above repulsive potentials, coefficients α, β, and γ areweighting coefficients and in the present embodiment, α=3, β=1, and γ=3.The values α, β and γ affect the dispersiveness of dots. The values α, βand γ can be actually determined by, for example, experimentaloptimization based on print images printed using the masks.

The coefficient s(n) is used for an multiplying in addition to γ inorder to disperse overlapping dots. The coefficient s(n) has a valuecorresponding to the number of overlaps so as to increase the degree ofdispersion of the dots consistently with the number of overlaps. Thepresent inventor experiments show that an appropriate dispersion can beachieved by using s(n) determined by either of the two equations:

$\begin{matrix}{{s(n)} = {{\sum\limits_{i = 1}^{n}{{nCi}\mspace{14mu} {or}\mspace{14mu} {s(n)}}} = {\sum\limits_{i = 1}^{n - 1}{nCi}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

That is, when the n denotes the number of overlaps, the sum of numbersof combinations is denoted by s(n). Specifically, for an object dot forwhich repulsive force is to be calculated, overlapping dots (which arelocated at the same position as that of the object dot on the same planeor different planes) and overlapping dots located at the distance r fromthe object dot are searched. In this case, n denotes the number ofoverlaps common to overlapping of the object dot and the dot on the sameplane and the different planes, which overlap the object dot at the sameposition, and overlapping of the dots which are located at the distancer from the object dot, on respective planes, and overlap each other inthe same manner. Then, for these two positions, repulsive forcesresulting from the overlapping dots are considered.

In the case of considering an example in which for two positions, dotsare present commonly on a first plane, a second plane and a third plane,n is defined as 3. Then, repulsive force attributed to the overlappingof the three dots is allowed to act on these positions. Here, when therepulsive force resulting from the overlapping of the three dots isconsidered, the repulsive force of the overlapping of every two dots andthe repulsive force of each dot are considered to act in a multiplexingmanner together with the repulsive force of the overlapping of the threedots. In other words, with the third plane not taken into account, theoverlapping may be considered to occur between two dots on the firstplane and the second plane. With the second plane not taken intoaccount, the overlapping may be considered to be the one between twodots on the first plane and the third plane. With the first plane nottaken into account, the overlapping may be considered to occur betweentwo dots on the second plane and the third plane. To calculate themultiplexing effect of overlapping of the dots, the repulsive forceresulting from the combination of overlaps is defined and s(n) such asthe one described above is used. The experiments show that this makes itpossible to provide a highly dispersive dot arrangement.

When the total energy is determined which is equal to the sum of therepulsive potentials of all the dots, as described above, processing isexecuted to reduce the total energy.

This processing involves sequentially shifting each of the dots to oneof the allocable positions located at a distance r of at most 4, atwhich position the repulsive potential of the shifted dot mostdecreases. This processing is repeated to reduce the total energy thatis equal to the sum of the repulsive potentials of all the dots. Inother words, the process of gradually reducing the total energycorresponds to the process of sequentially making the arrangement of thedots more dispersive, that is, the process of gradually reducing lowfrequency components of the dots.

Then, the rate of a decrease in total energy is calculated. If the rateis determined to be equal to or less than a predetermined value, theenergy attenuating process is ended. It should be noted that thepredetermined value can be determined, for example, on the basis of theresults of actual printing and corresponds to a decrease rate at whichan image with appropriately reduced low frequency components can beprinted. Finally, respective planes with the rate of a decrease in totalenergy equal to or less than the predetermined value are set as finalarrangements of the dots.

FIGS. 13A to 13D are diagrams schematically showing the repulsivepotential calculation and total energy attenuating process, describedabove. More specifically, these figures include perspective viewsshowing the three planes A1, A2, and A3 according to the presentembodiment and plan views specifically showing movement of the dots. Inthe figures, the smallest squares show allocable positions of the dots.Positions overlapping each other among three overlapping planescorrespond to the same allocable positions among the planes.

FIG. 13A illustrates that when dots are present on the same plane, therepulsive force of these dots is added to (increases) the repulsivepotential. In the example shown in the figure, one dot is present on thesame plane A1 on which the dot Do of an object position is present atthe distance r from that position. In this case, α=3 is applied, and apotential 1×αE(r) is added as the potential of the object dot Do.

FIG. 13B is a diagram illustrating that dots are present on planes(planes A2 and A3) different from that on which the object dot Do ispresent and that a repulsive potential is added on the basis of therelationship between the object dot and these two dots. The relationshipbetween the object dot and these two dots is that between differentplanes. Then, β=1 is applied and a potential 2×βE(r) corresponding tothe two dots is added.

FIG. 13C is a diagram illustrating that dots are present on the sameplane on which the object dots is present and on planes different fromthat on which the object dot is present as is the case with the abovetwo figures, and in addition, a dot is present on the same position of adifferent plane and then that dot and the object dot overlap eachanother, and illustrating the repulsive potential based on therelationship among these dots. Not only the conditions shown in FIGS.13A and 13B are met but an dot is present at the same position on theplane A3, which is different from the plane A1 with the object dot Dopresent. Thus, the following potentials are added: the repulsivepotential 1×αE(r) of one dot on the same plane, the repulsive potential1×βE(0) of one dot on the different plane at the same position, therepulsive potential 2×βE(r) of two dots on the different planes, and therepulsive potential γs(2)×E(r) of overlapping to which γ=3 is applied ata overlap number n=2. As s result, in the dot arrangement shown in FIG.13C, the sum of the repulsive potentials associated with the presence ofthe object dot Do is 1×βE(0)+1×αE(r)+2×βE(r)+γs(2)×E(r).

FIG. 13D is a diagram illustrating that in the dot arrangement shown inFIG. 13C, movement of the dot Do changes the sum of repulsive potentialsof this dot. As shown in FIG. 13D, when the dot Do (located on the planeA1) shifts to an adjacent position on the same plane, the sum of therepulsive potentials associated with the presence of the dot Do changesinto βE (1)+1×αE(r2)+2×βE(r2) because the distance changes into r2 fromr and the number n of overlaps becomes 0. For the dot arrangement shownin FIG. 13C, the sum of the repulsive potentials 1×βE(0)+2×βE(r)+1×αE(r)+γs(2)×E(r) is compared with the sum of the repulsivepotentials resulting from movement of the dot Do in FIG. 13D. Thisdetermines a change in the sum of the repulsive potentials after themovement.

In the above description, the sum of the repulsive potentials isobtained by determining the sum of energies of the dots between twopositions, or of the dots among three positions when the dot is moved.However, this is for simplification and the sum of the repulsivepotentials is of course obtained by integrating the repulsive potentialson the basis of the relationship between the dot of interest and dotsincluding those of other possible positions other than the above dots.

If, of the dots for each of which the sum of the repulsive potentials iscalculated as shown in FIGS. 13A to 13C, for example the dot Do showsthe largest repulsive potential sum, changes in repulsive potentialafter the movement of the position of the pattern Do is determined asdescribed in FIG. 13D and the dot Do is moved to the position with mostdecreasing of repulsive potential sum. This processing is repeated toenable a reduction in the total energy of the three planes. That is, thedot arrangement of the superposing of the three planes is appropriatelydistributed with few low frequency components.

The dots are appropriately dispersed among the three superposed planesA1, A2, and A3, and thus, the dots are also appropriately dispersedamong the complementary masks in the case that these three masks arerespectively masks for the multi-pass print of two-passes. Further, thedots of superposing of an arbitrary number (2, 3, 4, or 5) of these 6planes are also appropriately dispersed and have few low frequencycomponents.

In the above description, the arrangement moving method is applied tothree plane masks which are used for the first pass and which areincluded in the masks for two passes. However, the arrangement movingmethod is not limited to this aspect but is applicable to all the planesto determine the arrangement of the dots. For the masks for two passprinting according to the present embodiment, the arrangement movingmethod is applicable to six plane masks for two passes. In this case,the range within which the dots are moved is not limited to nearbypixels. Arranged pixels may be moved on the basis of the relationshipbetween the corresponding dots on different planes. Specifically, forexample, a dot on one plane may be moved to a pixel on the same plane onwhich no dot is placed, and a dot placed on a pixel of another planewhich corresponds to the moved pixel may be moved to a pixel on the sameplane which corresponds the pixel on which the above dot was located.This makes it possible to change the arrangement relationship among thedots on all the planes involved in the repulsive potential calculation.Consequently, the positions of the dots can be changed to one another soas to minimize the potential energy.

Sequential Arrangement Method

This method is a method which sequentially arranges dots in a part of aplane where no dots have been arranged yet, as described above. Thismethod sequentially places an dot on three planes one by one, forexample, shown in FIGS. 13A to 13C and repeats this operation to arrangethe dots according to arrangement rate of each plane. In this case,before a dot has been arranged, calculation is made of the possiblerepulsive potential between the dot of that position and each of thedots already arranged on the planes A1, A2, and A3. The repulsivepotential can be calculated in the same manner as described above forthe arrangement moving method. The difference between the present methodand the arrangement moving method is that with reference to the exampleshown in FIGS. 13A to 13C, if in contrast to the above arrangementmoving method, the dot Do, shown in these figures, has not been placedyet but is to be newly placed, the repulsive potential is calculated onthe basis of the relationship between the dot Do and dots alreadyarranged on the same plane A1 and on the different plane A2 or A3. As isalso apparent from the description, at the initial stage where no dotshave been arranged yet, the repulsive potential has the same valueregardless of the position of the dot.

Next, among the repulsive potentials calculated under the assumptionthat the dot is placed on each of positions of the planes, a positionhaving the minimum potential energy is determined. If plural positionsshow the minimum energy, random numbers are used to determine one of theplural positions. In the present embodiment, the position with theminimum energy is determined under the condition that on the same plane,no dot is placed on a position on which an dot has already been placed.This is because depending on a parameter such as the weightingcoefficient or repulsive potential function, in the repulsive potentialcalculation, overlapping of dots on the same plane may result in theminimum energy as a result of the relationship between the object dotand dots on the other planes and because in this case, the overlappingis prohibited because only one dot is allowed to be placed on oneposition. An dot is placed on the determined position with the minimumpotential energy. That is, data on that position is set to “1”. Then,the method determines whether or not one dot has been placed on each ofthe planes A1, A2, A3. If this placement has not been finished, theprocessing is repeated.

When one dot has been sequentially placed on the planes A1, A2, and A3in this order, the method determines whether or not dots have beenarranged on up to 50% of all allocable positions. Once 50% of the dotshave been arranged on each of the three planes, the present process isfinished.

The above described sequential arrangement method also makes it possibleto produce planes having characteristics similar to those of planesproduced by the above arrangement moving method. That is, for the threeplanes obtained by the sequential arrangement method, the dots areappropriately dispersed in the superposed planes.

The above description is made in which a plane of the density patternand a plane of the mask are not distinguished from each other. However,as explained in an example below, the plane of the density pattern amongthe above planes or dots in the plane of the density pattern ispreviously determined as the density pattern, during the calculation ofthe repulsive force. That is, during the calculation of the repulsiveforce, dots in the plane corresponding to the density pattern are takenas fixed dots and the arrangement of these dots are not determined bymoving of dot positions and dot arrangements in accordance with therepulsive potential energy. That is, in the present embodiment, thetarget plane of determining dot arrangement is the plane correspondingto the mask, and the plane corresponding to the density pattern or dotsin that plane is a target of the calculation of the repulsive force.More specifically, when determining a dot arrangement of the planecorresponding to a mask, the term of the weighting coefficient α forcalculating the repulsive potential is applied to the plane of the mask.Further, terms of the coefficients β and γ are applied for thecalculation of the repulsive potential between the plane of the mask andeach of the plane corresponding to other mask and the planecorresponding to the density pattern.

Thus, the mutual interference can be reduced between the arrangement ofprint permitting pixels in a mask to be created and the density pattern,and also the arrangement pattern itself of print permitting pixels ofthe mask is made highly dispersed.

A specific example of methods for creating a mask by usingabove-mentioned basic method, in accordance with the present embodiment,will be described below for the method of creating 100% even mask fortwo pass printing.

Summary of the Embodiment

This embodiment relates to multi-pass printing of two-pass in which animage is completed by twice of scanning by using one print head equippedwith a nozzle array ejecting cyan (C) ink as a printing element. A maskused for the two-pass printing has a pattern whose interference with adensity pattern is reduced and which is well dispersed. This preventsdots formed by each scanning from being unevenly distributed in number.Furthermore, since dots are dispersedly formed in each scanning, even ifthere is a deviation of printing position for example, texture that maybe caused by the deviation is visually unobtrusive, thus suppressingadverse effects on image quality.

In two-pass printing, the nozzles of the print head are divided into afirst group of nozzles and a second group of nozzles, each groupincluding 256 nozzles. Masks (two masks C1 and C2) are associated withrespective groups and the size of respective masks C1 and C2 in asub-scan direction (conveying direction) is equivalent to 256 pixelsthat are the same as the number of the nozzles of respective groups.Since the masks C1 and C2 are complementary each other, superposingthese masks enables printing of the area corresponding to 256 (lateral)pixels×256 (longitudinal) pixels to be completed. As shown in FIG. 2,printing is performed on a area A of a print medium by using the maskC1, the print medium is conveyed by the length of 256 pixels and thenprinting is performed on the area A by using the mask C2. Printing of animage is completed by the twice pass.

Method of Creating Mask

A method of creating the mask in accordance with this embodiment will bedescribed regarding the case in which the mask is created by usingabove-mentioned sequential arrangement method.

FIG. 15 is a flow chart showing arrangement determination processing ofprint permitting pixels according to the sequential arrangement methodin accordance with this embodiment.

In processing shown in FIG. 15, the arrangement of print permittingpixels is performed at 50% of arrangement rate in such a way that aprint permitting pixel is sequentially arranged on one plane. In stepS701, firstly, the plane of mask C where print permitting pixels will bearranged and the plane of a density pattern are specified and repulsivepotential is calculated for the arrangement of print permitting pixelsin these planes. At this time, as described above, dots have beenalready arranged on the plane corresponding to the density pattern.Thus, while the dots remain fixed, repulsive force is calculated betweenthe dots and print permitting pixels to be arranged on the plane of maskC.

FIG. 16 is a diagram showing a concept for calculating repulsive forceregarding the arrangement of print permitting pixels on the mask C. Incalculating repulsive force, the density patterns (herein after alsoreferred as “dot arrangement pattern”) of planes P1 to P4 to beconsidered are fixed patterns. These dot arrangement patterns of planesP1 to P4 are predetermined for each of levels shown by index data. Inprocessing in which the arrangement of print permitting pixels of themask C is determined, the repulsive potential between print permittingpixels on the mask pattern C and the repulsive potential between printpermitting pixels on the mask pattern C and dots on the planes P1 to P4are calculated. Then, as described above, the arrangement of printpermitting pixels on the mask C is determined based on the result ofrepulsive potential calculation.

FIG. 17 shows dot arrangement patterns according to the presentembodiment. The dot arrangement patterns shown in FIG. 17 are composedby assembling a minimum unit pattern of 2 pixels×2 pixels, which isdescribed above in reference with FIG. 6, at four units in longitudinaldirection and four units in lateral direction. More specifically, in thepatterns shown in FIG. 17, pattern types 0 to 3 shown in FIG. 6 arearranged for respective index data levels (pattern of level 0 is notshown; all pixels are “white”), based on a rule according to the densitypattern selection matrix to make the pattern the size of which is 64pixels×64 pixels. It should be noted that FIG. 17 and figures thatfollow FIG. 17 show the pattern size of which is 8 pixels×8 pixels forsimplifying illustration.

Of the dot arrangement patterns for respective levels shown by indexdata, described above, the dot arrangement pattern of size of 256pixels×256 pixels corresponds to 256 pixels×256 pixels of the mask C.The arrangement of print permitting pixels of the mask C is determinedby considering the planes P1 to P4 that are dot arrangement patterns forrespective gradation levels. Specifically, the arrangement of printpermitting pixels is determined by using above-mentioned calculation ofrepulsive potential. The dot arrangement patterns to be considered,however, are not the repetitive 8 pixels×8 pixels patterns shown in FIG.17. This is because inequality of repulsive potential is removedbeforehand, which will be described later in detail.

FIG. 18 is a diagram showing the dot arrangements of the planes P1 to P4that are subjected to repulsive potential calculation in determining thearrangement of print permitting pixels on the mask C. The dotarrangement patterns of the planes P1 to P4 are obtained by separatingthe dot arrangement pattern shown in FIG. 17 into patterns that areexclusive each other. Specifically, for the original dot arrangementpattern shown in FIG. 17, i.e. the dot arrangement pattern used in thebinary data expansion processing shown in FIG. 5, the patterns (alsoreferred as to “dot pattern for calculation”) are represented by thedifference between respective dot arrangement patterns of respectivegradation levels. The pattern (L1-L0) of the plane P1 is obtained byremoving dots of the dot arrangement pattern of gradation level 0 (L0)from dots of the dot arrangement pattern of gradation level 1 (L1).Similarly, the pattern of the plane P2 is the dot pattern correspondingto the difference between the pattern of gradation level 2 (L2) and thepattern of gradation level 1 (L1); the pattern of the plane P3 is thedot pattern corresponding to the difference between the pattern ofgradation level 3 (L3) and the pattern of gradation level 2 (L2); andthe pattern of the plane P4 is the dot pattern corresponding to thedifference between the pattern of gradation level 4 (L4) and the patternof gradation level 3 (L3). Since the planes P1 to P4 are exclusivepatterns each other, dots would be arranged at the arrangement rate of100% that is the same rate of gradation level 4, when superposing allthe planes.

In calculating repulsive potential, the dot arrangement patterns aremade to be exclusive in order to prevent the inequality of the number ofprint permitting pixels arranged and the reduction of dispersibility dueto biased repulsive potential in a certain region. That is, each dotarrangement pattern shown in FIG. 17 preserves the dot arrangement ofthe former level when the level is increased. Therefore, if the dotarrangement pattern itself is used for calculating repulsive potential,the preserved dots are regarded as overlapping dots on different planes.However, since dots of the dot arrangement pattern to which a mask isapplied by masking processing are those of one of a plurality of levels,they do not have multiplex relation with the mask or do not interferewith the mask, as described above. Therefore, if the dot arrangementpattern itself is used for calculating repulsive potential, the valuesof repulsive potential calculated is biased in a certain region relativeto the actual relation, thus adversely causing the inequality of thenumber of print permitting pixels to be arranged and the reduction ofdispersibility.

Although the dot arrangement pattern in which the dot arrangement of theformer gradation level is preserved when the gradation level isincreased, is shown in the above example, the present invention is notlimited to the above example and also can be applied to the dotarrangement pattern in which the dot arrangement of the former gradationlevel is not preserved.

FIG. 19 shows one example of the dot arrangement patterns in which thedot arrangement of the former gradation level is not preserved as it iswhen the gradation level is increased. As shown in FIG. 19, in thearrangement pattern of level 1, for example, dots are arranged on pixels1301 and 1302. Compared to this arrangement, in level 2 where the levelis increased by one level, dots are not arranged on the pixel 1301 andthe dot arrangement of level 1 is not preserved, while dots are arrangedlikewise as the dot arrangement of level 1 on the pixel 1302. Thus,there is a dot arrangement pattern in which the dot arrangement of theformer level is not preserved completely (as it is).

In using the dot arrangement pattern in which the dot arrangement is notpreserved as it is when the level is increased, the dot arrangementpattern and exclusive pattern thereof are used for calculating repulsivepotential. In calculating repulsive potential, the pixels (for examplepixel 1301) which do not preserve the dot (arrangement) has the sameinfluence on print permitting pixels of the mask, if the distance is notconsidered. Meanwhile, the pixels (for example pixel 1302) whichpreserve dots has overlapping and multiplex relation with printpermitting pixels of the mask in calculating repulsive force. From thispoint of view, a dot arrangement pattern and the exclusive patternthereof are used as planes for calculating repulsive force.

FIG. 20 shows 8 planes used for calculating repulsive potential in thecase of the dot arrangement patterns shown in FIG. 19. In FIG. 20, theplane P1 has the dot arrangement pattern of level 1 shown in FIG. 19 andthe plane 2 has the exclusive dot pattern thereof. Similarly, the plane3 has the dot arrangement pattern of level 2 and the plane 4 has theexclusive dot pattern thereof; the plane 5 has the dot arrangementpattern of level 3 and the plane 6 has the exclusive dot patternthereof; and the plane 7 has the dot arrangement pattern of level 4 andthe plane 8 has the exclusive dot pattern thereof.

When the dot arrangement patterns shown in FIG. 19 are used, thecalculation of repulsive potential for determining the arrangement ofprint permitting pixels of the mask C is performed for the plane of themask C and the above-mentioned 8 planes, on which the dot arrangementsare fixed, for the plane of the mask C.

Referring to FIG. 15 again, after calculating repulsive potential asdescribed above, step S702 determines the position (pixel) havingminimum potential energy among the repulsive potentials calculatedwhenprint permitting pixels are placed in the arrangement position of themask C. Then, step S703 determines if there is more than one positionhaving minimum potential energy or not. If there is more than oneposition, step S707 determines one position of them by using a randomnumber. Then, step S704 arranges the print permitting pixel on thedetermined position having minimum potential energy.

Step S705 determines if print permitting pixels are arranged on theplane of the mask C up to 50% of the positions where pixels can bearranged or not. If not, the processing in step S701 and the subsequentsteps is repeated. When print permitting pixels are arranged up to 50%,this processing is terminated.

When the mask C1, which is the mask used for the first pass of two-passprinting, is set as described above, the mask C2, which hascomplementary relation with the mask C1, can be specified based on themask C1.

According to the method for creating a mask in this embodiment, asdescribed above, firstly, the arrangement of print permitting pixels inthe mask C created is well dispersed depending on above-mentionedweighting of α, β and γ. Secondly, print permitting pixels and dots arealso well dispersed on the superposing of the mask C and the planes P1to P4 of dot arrangement patterns considered in creating the mask C.That is, both the logical product and the logical sum of the printpermitting pixels arranged on the mask C and the dots arranged on eachof the planes P1 to P4 are dispersed. These logical product and logicalsum can be obtained between print permitting pixels arranged on the maskand dots arranged on each of the planes, for example, when 256pixels×256 pixels of the mask are associated with 256 pixels×256 pixelsof each of the planes.

The good dispersibility of above-mentioned logical sum ensures that, inboth the mask C1 and the mask C2 that has complementary relation withthe mask C1, the arrangement of print permitting pixels is welldispersed relative to the dot arrangement patterns shown in FIGS. 17 and17. This can suppress the biased formation of dots by a specificscanning.

Further, the good dispersibility of above-mentioned logical product alsoensures that the dot pattern obtained by mask-processing for dot dataaccording to the dot arrangement pattern shown in FIGS. 17 and 19, withthe use of the mask C1 (C2) are well dispersed. Such effects of thepresent invention is applicable to each embodiment describe below.

Consequently, when the dot patterns generated according to the dotarrangement patterns in FIG. 17 or 19 are printed, as to dots formed byeach scanning, their number is not unequally high in a specific scanningand dots are well dispersed, by using the mask of this embodiment. Thegood dispersibility makes texture that may occur due to various factorsvisually unobtrusive, thus suppressing adverse effects on image quality.

As described above, according to the mask creating method disclosed inJapanese Patent Application No. 2007-104268, a mask is obtained byconsidering the arrangement of a density pattern. Thus, the interferencebetween a mask and binary data generated using a density pattern can bereduced. As described above, a mask employed for this embodiment has asize corresponding to the density pattern selection matrix size, orcorresponding to the repetition cycle. That is, in a mask having acertain size, printing permitting pixels are determined in accordancewith the size of a corresponding density pattern selection matrix (or acorresponding dot arrangement pattern). Therefore, when the feedingamount is changed, the corresponding mask is used, and accordingly, thesize of a density pattern selection matrix is changed. Thereby, such aphenomenon can be prevented that binary data that have differentrepetition cycles based on a density pattern selection matrix arecorresponding to one mask that is used to print unit areas. As a result,the arrangement of print permitting pixels that is determined for a maskby considering the interference with binary data becomes effective, andthe interference between print data and the mask can be appropriatelyreduced.

In this embodiment, the method described in Japanese Patent ApplicationNo. 2007-104268 has been employed as an example mask manufacturingmethod while taking a density pattern into account. The method is notlimited to this, and a method described in, for example, Japanese PatentLaid-Open No. 5-31922 may also be employed.

When binary data is generated by a dither method, masks can also begenerated by considering the threshold value of a dither pattern. Thatis, for image data at the individual gradations, the ON/OFF positions ofprint data to be binarized by the dither pattern can be roughlyidentified in advance based on the characteristic of the dither pattern.Therefore, a mask pattern can be determined by considering the ON/OFFarrangement of print data that can be obtained in advance based on thedither pattern, i.e., by considering an interference of the thresholdvalue and the arrangement relative to print permitting pixels in a maskpattern.

Other Embodiment

In the first and second embodiments, an example for obtaining binarydata using the density pattern method has been described. However, thebinarization processing is not limited to this example. The presentinvention can be applied for any other mode that includes a pattern of aspecific size, which is repetitively employed for binary data generationto provide periodicity for binary data generation. For example, in thecase of a dither method for employing a dither pattern as a binarizationpattern, the size of a dither pattern can be changed in accordance witha change of a feeding amount. Assume in the first embodiment that thebinarization processing is to be performed using a dither pattern. Inthis case, a dither pattern of 64 pixels×64 pixels is selected at stepS1203 in FIG. 11, and a dither pattern of 84 pixels×84 pixels isselected at step S1206. In this manner, the size of a dither pattern tobe employed and the neighbor pattern can be a divisor of a conveyingamount.

Furthermore, in the above embodiments, a value of a cycle of binary dataobtained based on a density pattern selection matrix has been a divisorsmaller than a value of a feeding amount. However, a value of a cycle isnot limited to this, and a repetition cycle and a feeding amount may bethe same value. For example, when the feeding amount is equal to alength of 256 pixels, the repetition cycle of binary data generation forthe two-pass printing in the above embodiment has been defined as alength of 64 pixels. However, this cycle may be defined as a length of256 pixels that is equal to the feeding amount.

In addition, in the above embodiments, the binary data generationprocessing in FIG. 11 has been performed by a host; however, thisprocessing may be performed by a printing apparatus. In this case, it ispreferable that the printing apparatus employ a special hardwarecomponent, such as ASIC, to perform the binary data generationprocessing. When the printing apparatus performs the binary datageneration processing shown in FIG. 11, this apparatus serves as animage processing apparatus (image data generation apparatus).

Further Embodiments

The present invention is put into practice by executing program codes ofsoftware such as those shown in FIGS. 5 and 11, for example, whichimplements the functions of the above described embodiments, or by astorage medium storing such program codes. Further, the presentinvention is also put into practice by that the computer (CPU or MPU) ofthe system or apparatus reads the program codes to execute them. In thiscase, the program codes of the software themselves implement thefunctions of the above described embodiments, so that the storage mediumstoring the program codes constitute the present invention.

The storage medium storing such program codes may be, for example, afloppy disk, a hard disk, an optical disk, a magneto-optical disk, aCD-ROM, a magnetic tape, anon-volatile memory card, or a ROM.

In addition, if the functions of the above described embodiments areimplemented not only by the computer by executing the supplied programcodes but also through cooperation between the program codes and an OS(Operating System) running in the computer, another applicationsoftware, or the like, then these program codes are of course embracedin the embodiments of the present invention.

Furthermore, a case is of course embraced in the present invention,where after the supplied program codes have been stored in a memoryprovided in an expanded board in the computer or an expanded unitconnected to the computer, a CPU or the like provided in the expandedboard or expanded unit executes part or all of the actual process basedon instructions in the program codes, thereby implementing the functionsof the above described embodiments.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Laid-Open No.2007-207157, filed Aug. 8, 2007, which is hereby incorporated byreference herein in its entirety.

1.-10. (canceled)
 11. A data generating apparatus for generating binarydata used for performing printing on a printing medium by using aprinting head in which a plurality of nozzles are arranged, saidapparatus comprising: a setting part for setting a printing mode, inwhich a plurality of movements of the printing head are performed andthe printing medium is conveyed by a conveying amount smaller than anarranging width of the plurality of nozzles of the printing head betweeneach of the plurality of movements, to perform printing on an areacorresponding to the conveying amount; a selection part for selectingpattern data used for binarization having a number of pixels in aconveying direction of the printing medium, the number of pixelscorresponding to one-Kth (K is a positive integer) of a number of pixelsthat corresponds to the conveying amount in the printing mode set bysaid setting part, from a plurality of pattern data used forbinarization that differ in a number of pixels in the conveyingdirection of the printing medium from each other; and a generation partfor generating binary data corresponding to the area by using thepattern data selected by said selection part.
 12. A data generatingapparatus for generating binary data used for performing printing on aprinting medium by using a printing head in which a plurality of nozzlesare arranged, said apparatus comprising: a setting part for setting oneprinting mode of a plurality of printing modes including a firstprinting mode, in which M (M is an integer 2 or greater) times ofmovements of the printing head are performed and the printing medium isconveyed by a first conveying amount smaller than an arranging width ofthe plurality of nozzles of the printing head between each of the Mtimes of movements, to perform printing on an area having a widthcorresponding to the first conveying amount, and a second printing mode,in which N (N is an integer greater than M) times of movements of theprinting head are performed and the printing medium is conveyed by asecond conveying amount, which is smaller than the first conveyingamount, between each of the N times of movements, to perform printing onan area having a width corresponding to the second conveying amount; anda generation part for, when the first printing mode is set, generatingbinary data corresponding to the area having the width corresponding tothe first conveying amount by using first pattern data used forbinarization having a number of pixels in a conveying direction of theprinting medium, the number of pixels corresponding to one-Kth (K is apositive integer) of a number of pixels that corresponds to the firstconveying amount, and when the second printing mode is set, generatingbinary data corresponding to the area having the width corresponding tothe second conveying amount by using second pattern data used forbinarization that differs from the first pattern data and has a numberof pixels in the conveying direction, the number of pixels correspondingto one-Kth of a number of pixels that corresponds to the secondconveying amount.
 13. The data generating apparatus as claimed in claim11, wherein the binarization pattern is a pattern of a density patternselection matrix used for selecting a density pattern.
 14. The datagenerating apparatus as claimed in claim 11, wherein the binarizationpattern is a dither pattern.
 15. The data generating apparatus asclaimed in claim 11, wherein the number of pixels corresponding to adivisor of the number of pixels that corresponds to the conveying amountis the same as the number of pixels that corresponds to the conveyingamount of the printing medium.
 16. The data generating apparatus asclaimed in claim 11, further comprising a memory storing a mask used fordividing, the binary data generated by said generation part into aplurality of binary data corresponding to the plurality of movements,wherein said mask is generated based on the pattern data.
 17. The datagenerating apparatus as claimed in claim 11 wherein the data generatingapparatus is a printing apparatus that performs printing on the printingmedium with use of the printing head, or a host computer for supplyingthe binary data to the printing apparatus.
 18. A printing apparatus forperforming printing on a printing medium by using a print head in whicha plurality of nozzles are arranged, said apparatus comprising: asetting part for setting one printing mode of a plurality of printingmodes including a first printing mode, in which M (M is an integer 2 orgreater) times of movements of the printing head are performed and theprinting medium is conveyed by a first conveying amount smaller than anarranging width of the plurality of nozzles of the printing head betweeneach of the M times of movements, to perform printing on an area havinga width corresponding to the first conveying amount, and a secondprinting mode, in which N (N is an integer greater than M) times ofmovements of the printing head are performed and the printing medium isconveyed by a second conveying amount, which is smaller than the firstconveying amount, between each of the N times of movements, to performprinting on an area having a width corresponding to the second conveyingamount; and a generation part for, when the first printing mode is set,generating binary data corresponding to the area having the widthcorresponding to the first conveying, amount by using first pattern dataused for binarization having a number of pixels in a conveying directionof the printing medium, the number of pixels corresponding to one-Kth (Kis a positive integer) of a number of pixels that corresponds to thefirst conveying amount, and when the second printing mode is set,generating, binary data corresponding to the area having, the widthcorresponding to the second conveying amount by using second patterndata used for binarization that differs from the first pattern data usedfor binarization and has a number of pixels in the conveying direction,the number of pixels corresponding to one-Kth of a number of pixels thatcorresponds to the second conveying amount.
 19. A data generating methodof generating binary data used for performing printing on a printingmedium by using a print head in which a plurality of nozzles arearranged, said method comprising: a setting step of setting a printingmode, in which a plurality of movements of the printing head areperformed and the printing medium is conveyed by a conveying amountsmaller than an arranging width of the plurality of nozzles of theprinting head between each of the plurality of movements, to performprinting on an area corresponding to the conveying amount; a selectionstep of selecting pattern data used for binarization having a number ofpixels corresponding to one-Kth (K is a positive integer) of a number ofpixels that corresponds to the conveying amount in a conveying directionof the printing medium in the printing mode set by said setting step,from a plurality of pattern data that differ in a number of pixels inthe conveying direction from each other; and a generation step ofgenerating binary data corresponding to the area by using, the patterndata selected by said selection step.
 20. A computer-readable storagemedium storing a program that is read by a computer and causes thecomputer to execute the data generation method as claimed in claim 19.